The present invention relates to a liquid crystal display apparatus, in particular, to a liquid crystal display apparatus provided with an effective function for producing a reflective color display.
A conventional reflective color liquid crystal display apparatus, which comprises a reflector provided with many micro-protrusions formed of resin, is disclosed in JP-A-4-243226 (1992). A color filter for a reflective color liquid crystal display apparatus is disclosed in JP-A-6-230364 (1994) and other publications. The color filter will not create any problems in the driving of a liquid crystal, such as when an optical reflector causes an electrical short circuit with transparent electrodes via a defect in the color filter, if the reflector is patterned to a shape approximately the same as the shape of the color filter.
A reflector comprising many fine protrusion-depression reflecting planes, whereon circular protrusions or depressions are arranged irregularly so as not to generate optical interference, has been proposed.
Furthermore, JP-A-10-177106 (1998) discloses a liquid crystal display apparatus, in which a liquid crystal element comprises a reflector, which is made to collect incident light in a specified direction by forming circular protrusions or depressions having unsymmetrical distribution of slope angles in their cross sectional shape.
In accordance with the prior techniques described above, the use of a black matrix becomes unnecessary, because the liquid crystal driving will not create any problems, such as when an optical reflecting film forming a reflector causes an electrical short circuit with transparent electrodes via a defect of a color filter, if the reflector is patterned to a shape approximately the same as the shape of the color filter, and so unnecessary reflection of light from an unopened portion can be prevented. However, the color filter for a reflective color liquid crystal display apparatus has a problem in that contrast is decreased with an element structure having no black matrix layer, depending on the display mode (for instance, normally open mode), because the color filter for a reflective color liquid crystal display apparatus must have spectral characteristics positively utilizing the light in a certain wavelength region, which should be shielded naturally.
Because a liquid crystal layer having a uniform thickness could not be formed with the composition of the liquid crystal display devices described above, wherein only a color filter layer was formed on a surface-roughened reflector, the color filter had an additional problem in that the quality of display (brightness and contrast) was decreased.
In accordance with the prior liquid crystal display devices, if a leveling layer was provided on the color filter layer for forming a liquid crystal layer having an uniform thickness, a problem, such as a decrease of the brightness, and other problems were generated.
The prior liquid crystal display devices had a problem in that the display was dark, because, in order to prevent coloring caused by optical interference by arranging circular protrusions or depressions irregularly in a region corresponding to pixel electrode portions, the number of protrusions or depressions, which were reflecting elements for controlling incident light, was decreased significantly from a case in which the protrusions or depressions were arranged in a closely packed manner.
In accordance with the prior liquid crystal display devices, reflected light was collected in a specified direction by making the slope angle distribution of the circular protrusions or depressions unsymmetrical. Therefore, there was a problem, such as difficulty in controlling the shape of the fine protrusions or depressions, because the manufacturing process became complex.
Furthermore, in accordance with the prior liquid crystal display devices, fine circular protrusions or depressions were formed by a photolithography method. Therefore, there was a problem, such as a high cost of manufacture, because the manufacturing process was complex, and the number of manufacturing steps was large.
The object of the present invention is to provide a liquid crystal display apparatus comprising a reflector having preferable reflecting characteristics by solving the above described problems, and to provide a method of manufacture thereof.
As a first means for achieving the above object, the reflective color liquid crystal display apparatus of the present invention uses the following liquid crystal display construction.
The liquid crystal display apparatus comprises an electrode substrate, wherein a reflector composed of a metal, such as aluminum, silver, and the like, is deposited on many fine protrusions and depressions formed on a resin layer, wherein a black pigment having a light shielding function is dispersed, and the resin layer is disposed on a glass substrate. Color filters of red, green, and blue having a leveling function are formed on the reflector; and transparent electrodes and an alignment layer are formed on the color filters. The liquid crystal display apparatus has another electrode substrate, wherein transparent electrodes and an alignment layer are formed on a glass substrate. The liquid crystal display apparatus is manufactured by joining the electrode substrates via a spacing material for defining the thickness of the liquid crystal so that each of the alignment layers face each other, filling liquid crystal into the interval between the electrode substrates by any method such as a vacuum filling method and the like, and sealing the interval.
As a second means for achieving the above object, the reflective color liquid crystal display apparatus of the present invention has a reflector composed by laminating a polymer layer having protrusions and depressions and a reflective layer onto a glass substrate. The reflector comprises the polymer layer, whereon fine protrusion-depression planes are formed by the following method and the like in order to achieve the above object.
1) string-shaped protrusions having smooth curves, or string-shaped depressions are arranged continuously and alternately;
2) string-shaped protrusions having a smooth curve are arranged continuously; and
3) string-shaped depressions having a smooth curve are arranged continuously.
In the reflector of the reflective liquid crystal display apparatus of the present invention, fine protrusion-depression planes are formed on the polymer layer by arranging the string-shaped protrusions or the string-shaped depressions in such a manner that the slope angle distribution of the cross sectional shapes of the depressions, and depressions in a direction at a right angle to the longitudinal direction, is approximately symmetrical from right and left, and the total lengths of the respective string-shaped protrusions or string-shaped depressions in respective directions are approximately equal.
In the reflector of the reflective liquid crystal display apparatus of the present invention, fine protrusion-depression planes are formed on the polymer layer by arranging the string-shaped protrusions or the string-shaped depressions in such a manner that the slope angle distribution of the cross section shapes of the depressions, and the depressions in a direction at a right angle to the longitudinal direction, is approximately symmetrical from right and left, and the total lengths of the respective string-shaped protrusions or string-shaped depressions in respective directions differ from each other.
The reflective liquid crystal display apparatus of the present invention is featured in having an electrode substrate formed by a polymer layer, which comprises fine protrusion-depression planes composed of string-shaped protrusions and string-shaped depressions, a reflective layer, an insulating layer, transparent electrodes, and an alignment layer laminated on a glass substrate; and another electrode substrate comprising a black matrix layer, color filters, a leveling layer, transparent electrodes, and an alignment layer laminated on a glass substrate; wherein the substrates are arranged so that the transparent electrodes of the above respective electrode substrates face each other on either side of the liquid crystal layer.
The reflective liquid crystal display apparatus of the present invention is featured in having an electrode substrate formed by polymer layers, wherein a black pigment and the like is dispersed, comprising fine protrusion-depression planes composed of string-shaped protrusions and string-shaped depressions, rectangular reflective layers arranged only at portions corresponding to the pixels, color filters, leveling layers, transparent electrodes, and alignment layers laminated on a glass substrate; and another electrode substrate comprising transparent electrodes, and alignment layers laminated on a glass substrate; wherein the substrates are arranged so that the transparent electrodes of the above respective electrode substrates face each other on either side of the liquid crystal layer.
The reflective liquid crystal display apparatus of the present invention is featured by a protrusion-depression pattern composed of protrusions or depressions formed by a simulation method of phase separation pattern generation by spinodal decomposition, the protrusion-depression pattern being used as a black matrix pattern for a photo mask used in forming the polymer layer, or a master pattern for a protrusion-depression pattern formed in a transcription die.
In the formation of the reflective liquid crystal display apparatus of the present invention, the simulation method for pattern generation by spinodal decomposition is a numerical simulation using:
1) Cahn-Hilliard-Cook equation,
2) Time dependent Ginzburg-Landau equation
3) Cell-Dynamical-System equation, and others.
In the formation of the reflective liquid crystal display apparatus of the present invention, the pattern of a black matrix portion or the pattern of a transparent portion for the photo mask used in forming the reflector is either a pattern generated by simulation of the spinodal decomposition, or a pattern obtained by image processing of the pattern generated by simulation of the spinodal decomposition and taken into a computer and the like.
In the formation of the reflective liquid crystal display apparatus of the present invention, the pattern generated by the simulation method is either a pattern indicating reflecting characteristics which are uniform in all directions, or a pattern indicating reflecting characteristics in which incident light is collected in a specified direction.
In the reflective liquid crystal display apparatus of the present invention, the liquid crystal display elements comprise a reflective electrode substrate, composed by laminating a reflector formed on a polymer layer comprising smooth protrusion-depression planes composed of a string-shaped pattern, which can be arranged in a closely packed manner, an insulating layer, plural transparent electrodes, and an alignment layer on one side of a glass substrate; a color filter substrate, composed by laminating a black matrix layer, color filters, a leveling layer, plural transparent electrodes, and an alignment layer on one side of another glass substrate; and liquid crystal filled in an interval between the reflective electrode substrate and the color filter substrate.
The manufacture of the reflective liquid crystal display apparatus of the present invention includes a method of forming a reflection electrode substrate, comprising the steps of: applying a photosensitive resin onto a glass substrate, and forming a polymer layer comprising smooth protrusion-depression planes composed of string-shaped protrusions and string shaped depressions using a transcription casting roll, or a template, and the like having protrusions and depressions satisfying predetermined conditions; forming a reflective layer onto the polymer layer, and forming an insulating layer onto the reflective layer, forming transparent electrodes onto the insulating layer, and forming an alignment layer onto the transparent electrodes. The manufacture of the reflective liquid crystal display apparatus further includes a method of forming a color filter substrate comprising the steps of: forming a black matrix layer onto one side of another glass substrate, forming color filters onto the black matrix layer, forming a leveling layer onto the color filter, forming transparent electrodes onto the leveling layer, and forming an alignment layer onto the transparent electrodes. Then, liquid crystal materials is filled into an interval between the reflection electrode substrate and the color filter substrate, and the interval is sealed.
Furthermore, the method of manufacturing the reflective liquid crystal display apparatus of the present invention comprises forming a reflector on a glass substrate, whereon a polymer layer comprising smooth protrusion-depression planes satisfying at least one of the following conditions has been formed:
1) a string-shaped pattern having smooth curves;
2) a pattern wherein string-shaped protrusions and string-shaped depressions are arranged so that the protrusions and depressions are arranged continuously, or the protrusions or the depressions are arranged continuously; and
3) a pattern wherein sums of total length components in any direction of the protrusions and corresponding direction of the depressions are approximately equal, or the sums of the total length components in respective directions of the protrusions and that of the depressions are different from each other.
The method of manufacturing a reflective liquid crystal display apparatus includes forming a reflection electrode substrate comprising the steps of: applying a photosensitive resin onto a side of a glass substrate to form a polymer layer comprising smooth protrusion-depression planes by patterning the polymer layer with a transcription casting roll, or a template, and the like, whereon the pattern is formed to satisfy the above conditions; shaping the polymer layer comprising the protrusion-depression planes to smooth the protrusion-depression planes by irradiating light or heat treating the substrate; forming a reflective layer onto the polymer layer comprising the smooth protrusion-depression planes; forming a leveling layer onto the reflective layer, forming plural transparent electrodes onto the leveling layer, and forming an alignment layer onto the transparent electrodes. The method of manufacture also includes forming a color filter substrate comprising the steps of: forming a black matrix layer onto another glass substrate, forming color layers onto the black matrix layer, forming a leveling layer onto the coloring layers, forming plural transparent electrodes onto the leveling layer, and forming an alignment layer onto the transparent electrodes. The method of manufacture further comprises the steps of joining the respective substrates with the alignment layers facing each other, filling liquid crystal into an interval between the reflection electrode substrate and the color filter substrate, and sealing the interval. The method of manufacturing the reflective liquid crystal display apparatus further comprises the steps of adhering a designated phase plate and polarizer on the surface of the glass substrate other than the surface whereon the color filters of the liquid crystal display element are formed, connecting a tape carrier package (hereinafter called TCP) whereon an IC for driving the liquid crystal is mounted, and an external circuit for driving to the liquid crystal display element, and assembling the liquid crystal display element into a frame, case, and the like.
Another method of manufacturing a reflective liquid crystal display apparatus involves manufacturing a reflective liquid crystal display element having a reflector, wherein the reflector is formed on a glass substrate having many fine protrusions or depressions formed thereon. The method of manufacturing a liquid crystal display element includes forming a reflection electrode substrate comprising the steps of: applying a photosensitive resin onto a side of a glass substrate and, subsequently, forming a polymer layer comprising smooth protrusion-depression planes, whereon string-shaped protrusions and string-shaped depressions are arranged continuously and alternately, by patterning the polymer layer by heat treatment after exposing and developing the photosensitive resin via a light shielding means, wherein the pattern is formed using a simulation of spinodal decomposition so that the string-shaped pattern comprises smooth curves having a uniform width and a designated length component in a black matrix region or a transparent region, and the sum of the length components in the black matrix region or transparent region become approximately equal each other in respective directions; forming a reflective film on the polymer layer having the protrusion-depression planes, forming a leveling layer on the reflective layer, and forming plural transparent electrodes on the leveling layer. The method of manufacture also includes forming a color filter substrate comprising the steps of: forming a black matrix layer onto another glass substrate, forming color filters onto the black matrix layer, forming a leveling layer onto the color filters, and forming plural transparent electrodes onto the leveling layer. The method of manufacture further comprises the steps of jointing the respective substrates with the transparent electrodes facing each other, filling liquid crystal into an interval between the reflection electrode substrate and the color filter substrate, and sealing the interval. The method of manufacturing a reflective liquid crystal display apparatus is completed by adhering a designated phase plate and polarizer on the surface of the glass substrate other than the plane whereon the color filters of the liquid crystal display element are formed, connecting TCP, whereon an IC for driving the liquid crystal is mounted, and an external driving circuit to the liquid crystal display element, and assembling the liquid crystal display element into a frame, case, and the like.